msm: display: panel frame rate report

Add metadata ioctl for retrieving panel frame rate.
Get ready to remove reserved fields usage.

Change-Id: I51a4aed9d85efd5f83a184100b6a3dc682c7a67c
Signed-off-by: Ken Zhang <kenz@codeaurora.org>

Conflicts:
	drivers/video/msm/msm_fb.c
	include/linux/msm_mdp.h